The Zohar opens this parasha with Rabbi Shimon saying “, הַמִּשְׁפָּטִים וְאֵלֶּה”, “Now these are the ordinances which you shall set before them”, these are the laws of reincarnation. The laws for the souls coming back to this world, according to the judgment they had received based on their prior life actions.
When the Torah says “חִנָּם יֵצֵא לַחָפְשִׁי וּבַשְּׁבִעִת יַעֲבֹד שָׁנִים שֵׁשׁ עִבְרִי עֶבֶד תִקְנֶה כִּי”, If thou buy a Hebrew servant, six years he shall serve; and in the seventh he shall go out free for nothing.”, This reveals some of the secrets of reincarnation. The soul returns to the world because of its sins, or because it didn’t complete Torah and Mitzvoth in its life. By those laws, the soul is forced to come back dressed in a physical body.